Clinical diagnosis of allergic contact dermatitis has historically utilized patch testing. This involves applying suspected allergens to the intact skin of a patient's back for 48 hours under occlusion with tape, and then observing the back at intervals for one week after application. Patch testing has good sensitivity and specificity, but there are a number of difficulties with this testing modality. Many patients find it inconvenient or impossible to keep their backs dry for the week-long testing procedure; this is especially difficult for patients whose occupation involves manual labor or those who live in a humid climate. Children find it particularly difficult to tolerate patches on the back due to their high activity levels, and, in young children, the temptation to prematurely remove the patches due to mild itching. Atopy patch testing has been utilized to study allergy to proteins such as dust mite in atopic patients. These proteins are larger molecules that poorly penetrate intact stratum corneum; but may be very relevant to patients with atopic dermatitis who often have non-intact skin barrier due to scratching. Technology that would allow allergens to move through the stratum corneum without prolonged occlusion are desirable. Removal of the stratum corneum with a laser prior to application of test allergens could preclude the need for tape occlusion of the test sites, thus avoiding many of the logistical problems with the current testing methods. Use of the laser may also allow a standardized way to facilitate introduction of protein allergens for atopy patch testing. The purpose of this study is to investigate the utility, safety, and patient satisfaction of laser assisted penetration of allergens in the investigation of contact dermatitis and atopic dermatitis.